Author(s): RAPPELT, L., HELD, S., MÜHLENHOFF, S., WIEDENMANN, T., MICKE, F., DONATH, L., Institution: GERMAN SPORT UNIVERSITY COLOGNE: DEUTSCHE SPORTHOCHSCHULE KOLN, Country: GERMANY, Abstract-ID: 2463

INTRODUCTION:
World-class endurance athletes exhibit very high total daily energy expenditures (TDEE). To normalize these values across athletes, TDEE is often stated as a multiple of the basal metabolic rate (BMR). While across short time frames athletes may exceed 5 times the BMR, evidence suggests that the maximal amount of energy expenditure that can be sustained over extensive periods of time will asymptoticly approach ~ 2.5 times BMR (Best et al., 2025). However, longitudinal data of elite athletes is still scarce.
METHODS:
To investigate long-term patterns of TDEE, five internationally successful German rowers (Tier 4-5 (McKay et al., 2022); 3 female, 2 male; age 25.2 ± 3.6 years) were monitored across 992 ± 153 consecutive training days [range: 809-1,155]. All training sessions (1,769 ± 956 per athlete; range: 812-3,259) and daily sleep duration were recorded. During the monitoring period, athletes completed repeated spiroergometric step tests (9.4 ± 1.7 per athlete; range: 8-12) at irregular intervals on a rowing ergometer. Individual heart rate-V̇O2 relationships were modeled and used to estimate metabolic equivalents (MET) and exercise energy expenditure (EE) for endurance training sessions. EE of non-endurance sessions was derived using the Adult Compendium of Physical Activities (Herrmann et al., 2024). BMR was estimated using the Harris-Benedict equation (Harris & Benedict, 1918), and TDEE was expressed in relation to BMR (xBMR). EE was quantified separately for sleep, leisure, exercise, and daily total across all monitored days and training days only. The highest consecutive-day TDEE values (expressed as xBMR) were subsequently modeled over time.
RESULTS:
Mean TDEE amounted to 15.8 ± 3.4 MJꞏday⁻¹ [range: 12.4-19.8 MJꞏday⁻¹] across all days and 17.4 ± 3.7 MJꞏday⁻¹ [14.4-22.6 MJꞏday⁻¹] on training days. Expressed relative to BMR, average daily energy expenditure corresponded to 2.05 ± 0.16 xBMR [1.82–2.24] across all days and 2.26 ± 0.10 xBMR [2.16-2.39] on training days. Peak observed TDEE reached 28.2 ± 9.0 MJꞏday⁻¹ [18.7-41.7 MJꞏday⁻¹], corresponding to 3.64 ± 0.79 xBMR [2.75-4.85]. Exercise contributed 6.90 ± 2.07 MJꞏday⁻¹ [5.16-9.76 MJꞏday⁻¹], while leisure and sleep accounted for 8.54 ± 1.30 MJ·day⁻¹ [7.47-10.6 MJꞏday⁻¹] and 2.49 ± 0.41 MJꞏday⁻¹ [2.13-3.08 MJꞏday⁻¹], respectively.
CONCLUSION:
Despite prolonged high training volumes across multiple seasons, average daily energy expenditure in elite rowers remained below the proposed ~2.5 xBMR metabolic ceiling, with only transient peak values exceeding this threshold.

References:
McKay et al., Int J Sports Physiol Perform., 2022
Herrmann et al., J Sport Health Sci., 2024
Harris & Benedict, Proc Natl Acad Sci U S A, 1918